Memory of texture during HDDR processing of NdFeB

Gutfleisch, Oliver; Khlopkov, K.; Teresiak, A.; Müller, K.‐H.; Dražić, Goran; Mishima, C.; Honkura, Y.

doi:10.1109/tmag.2003.815749

Cited by 74 publications

(26 citation statements)

References 18 publications

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“…Although the shape of lamellar cluster after the HD step was different, above microstructural change during DR step was similar even when P HD was 100 kPa. orientation between α-Fe and NdH 2 grains in the disproportionated stage was reported previously, [8][9][10][11][12][13][14] and from the present study, such an orientation relationship is found to be maintained even when the DR process is under progress. On the other hand, no relationship among recombined Nd 2 Fe 14 BH y grains as well as between Nd 2 Fe 14 BH y and α-Fe or NdH 2+x grains was observed at this stage.…”

Section: Resultssupporting

confidence: 89%

“…There are some reports suggesting the possible role of Fe 2 B as a memory site in the induction of the anisotropy, 11,14,16 however in the present study, the detection of iron boride phase was difficult, particularly in the DR step, and the role of B is still unclear. Considering that the amount of Fe 2 B formed during the HDDR process is small, an adequate control of reaction speed that maintains the orientation relationship between α-Fe and NdH 2 seems rather important.…”

Section: -6mentioning

confidence: 56%

“…7 Along with efforts to obtain the higher degree of anisotropy, investigations of the mechanism that induces such a crystallographic alignment have been intensively performed to date. [7][8][9][10][11][12][13][14][15][16] Further, from the microstructural observation as well as the analysis of orientations of crystal grains, it is now recognized that the α-Fe and NdH 2 grains formed during the HD process tend to align with some type of crystallographic orientation. [8][9][10][11][12][13][14] Currently, there are several reports that describe the details of such an orientation observed at the state where the HD step was completed; however, not enough information is available on the alignment behavior during the DR process.…”

Section: Introductionmentioning

confidence: 99%

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Crystallographic alignment in the recombination stage in d-HDDR process of Nd-Fe-B-Ga-Nb powders

et al. 2016

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Nd-Fe-B-Ga-Nb magnetic powder was subjected to the dynamic hydrogen disproportionation desorption recombination treatment. For samples disproportionated at both 30 and 100 kPa of hydrogen pressure, the changes in the microstructure and grain orientation during recombination process were investigated. It was observed that even during the recombination process, the orientation relationship was maintained between α-Fe and NdH2+x grains formed after the disproportionation treatment at 30 kPa of hydrogen pressure, [110]α-Fe // [110]NdH2+x, (-110)α-Fe // (-220)NdH2+x. Additionally, the alignment of recombined Nd2Fe14BHy grains became clear after 30 min of DR treatment showing following orientation relationship: (001)Nd2Fe14BHy // (110)α-Fe and (110)NdH2+x. In contrast, such a relationship was not observed in the sample disproportionated at 100 kPa of hydrogen pressure. This difference in the degree of alignment was also confirmed by measuring the magnetic property of the respective samples.

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Section: Resultssupporting

confidence: 89%

Section: -6mentioning

confidence: 56%

Section: Introductionmentioning

confidence: 99%

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Crystallographic alignment in the recombination stage in d-HDDR process of Nd-Fe-B-Ga-Nb powders

et al. 2016

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“…It has been known that the texture in HDDR materials is closely related to the presence of the Fe 2 B phase in the disproportionate state, which has the same tetragonal structure as that of the Nd 2 Fe 14 B mother phase [4,5]. The Fe 2 B phase crystals can keep their crystallographic orientation the same as that of the mother phase and act as a nucleation site for the Nd 2 Fe 14 B phase during the recombination, thus leading to a texture.…”

Section: Resultsmentioning

confidence: 99%

“…The disproportionation reaction of the HDDR technique is the most critical step for controlling the magnetic properties of the Nd-Fe-B HDDR powder [1][2][3][4][5][6][7]. It has been widely known that the Nd-Fe-B alloy fully disproportionated in hydrogen consists of a multi-phase mixture of NdH x , Fe 2 B, and α-Fe, and the final magnetic properties (in particular, the grain texture) of the HDDR material are affected heavily by the phase constitution in the disproportionated state [4,5]. Therefore, it is important to understand precisely the phase constitution of the fully disproportionated material.…”

Section: Introductionmentioning

confidence: 99%

TMA Study on Phase Evolution During Hydrogen-assisted Disproportionation of Nd-Fe-B Alloy

Kwon¹,

Yu²

2011

Journal of Magnetics

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Phase evolution during the hydrogen-assisted disproportionation of Nd 12.5 Fe 80.6 B 6.4 Ga 0.3 Nb 0.2 alloy was investigated mainly by using a magnetic balance-type thermomagnetic analyser (TMA). In order to avoid any undesirable phase change in the course of heating for TMA, a swift TMA technique with very high heating rate (around 2 min to reach 800 o C from room temperature) was adopted. The hydrided Nd 12.5 Fe 80.6 B 6.4 Ga 0.3 Nb 0.2 alloy started to be disproportionated in hydrogen from around 600

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Influence of Colloidal Additivation with Surfactant‐Free Laser‐Generated Metal Nanoparticles on the Microstructure of Suction‐Cast Nd–Fe–B Alloy

Liu,

Yang,

Staab

et al. 2023

Adv Eng Mater

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Development of new powder feedstocks using nanoparticles (NPs) has the potential to influence the microstructure of as‐built parts and overcome the limitations of current powder‐based additive manufacturing (AM) techniques. The focus of this study is to investigate the impact of NP‐modified magnetic microparticle powder feedstock on the microstructure of suction‐cast Nd‐Fe‐B‐based alloys. This particular casting method has been recognized for its ability to replicate, to some extent, the melting and rapid solidification stages inherent to metal powder‐based AM techniques such as Powder Bed Fusion using a Laser Beam (PBF‐LB). Two types of NP materials, Ag and ZrB2, are used, and their effects on the grain size distribution and dendritic structures are evaluated after suction casting. Ag NPs result in smaller, more uniform grain sizes. ZrB2 NPs result in uniformly distributed grain sizes at much lower mass loadings. The results show that feedstock powder surface modification with low‐melting‐point metal NPs can improve permanent magnets’ microstructure and magnetic properties, at below 1 vol.%, equal to sub‐monolayer surface loads. This study highlights the potential of using NPs to develop new powder feedstocks for AM, significantly improving the final part’s properties.This article is protected by copyright. All rights reserved.

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Memory of texture during HDDR processing of NdFeB

Cited by 74 publications

References 18 publications

Crystallographic alignment in the recombination stage in d-HDDR process of Nd-Fe-B-Ga-Nb powders

Crystallographic alignment in the recombination stage in d-HDDR process of Nd-Fe-B-Ga-Nb powders

TMA Study on Phase Evolution During Hydrogen-assisted Disproportionation of Nd-Fe-B Alloy

Influence of Colloidal Additivation with Surfactant‐Free Laser‐Generated Metal Nanoparticles on the Microstructure of Suction‐Cast Nd–Fe–B Alloy

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